多级存储体系(续1 LO Smaller faster register CPU registers hold words retrieved from and costlier L1 on-chip L1 per byte) cache(SRAM) storage L1 cache holds cache lines retrieved devices from the L2 cache cache( SRAM) L2 cache holds cache lines etrieved from memory L3 main memory (DRAM) Main memory holds disk slower blocks retrieved from local and cheaper (per byte) L4: local secondary storage storage (local disks devices Local disks hold files retrieved from disks on remote network servers remote secondary storage (distributed file systems, Web servers)多级存储体系(续1)